Mercury switch



Mh 22, p K CRAMBLET MERCURY SW1 TCH Filed April 23, 1928 IN VEN TOR.

, Mahr @j I la i 4% ATTORN Y.

. stantial areas to Fatented @STAB A @@RGBTEN 01e DELAWARE ME'CURY Si?! Application led April 2S,

- glass and metal parts, and this without the till necessity of utilizing highly skilled and expensive labor.

Another object of the invention resides in the provision, in a mercury switch of the type having an outer envelope or container of glass or other suitable material and a body of mercury in the container serving to make and break an electrical circuit, of metallic closuresfor the openings in the outer envelope or of other metallic elements incorporated in the switch construction which serve as electrodes and also take the place of the lead-in wires heretofore used. The metallic closures or other metallic elements are welded and sealed to the outer glass container or other glass structure of the switch in a novel manner which eliminates the necessity of having a. skilled glass blower or worker close olf the openings of the switch after the various switch elements have been assembled in the outer container. By having direct contact with or by having extensions contacting with the mercury, the metallic closures eliminate the necessity of using separate electrodes. Moreover, the metallic closures are designed to engage clips, binding strips or other electrical connectors and to transmit the current into the interior of the switch without the employment of lead-in wires which previously had to be provided and sealed in through the outer glass envelope by highly skilled labor.

ln general the invention provides a simple and durable mercury switch construction which is reliable and efficient in operation and which may he manufactured at a comparal92. Serial io. 272,224..

tively slight expense *from materials and by means of facilities ordinarily available and without the employment of highly skilled and expensive labor.

Other objects and advantages reside in certain novel features of the construction arrangement and combination of parts which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings forming a part of this specification, and in which:

Figure l is a view in longitudinal section showing one type of mercury switch which is constructed in accordance with the present invention;

Figure 2 is a similar view showing a slight modification of the switch shown in Figure l;

Figure 3 is a View in end elevation showing a slight variation in the construction of the metallic element or cap;

Figure 4 is a fragmentary view in centralil longitudinal vertical section showing the end portion of the switch equipped with the cap of Figure 3; and v Figure 5 is a sectional view showing another variation of the construction.

Referring to the drawings, and more especially to Figure l, the numeral 1 designates an outer container or envelope which may be of soft or hard glass or any suitable composition or material. An inner tube or sleeve 2 of arc resisting material such as hard glass quartz, porcelain, or the like, is positionedv within the container 1 and Xedly supported in spaced relation to the container by means of a ring or partition 3 of asbestos or other material. The ring 3 may be impregnated with cement if desirable and in any event serves to properly support the tube 2 on the container 1 without transmitting shocks and strains between the tube 2 and the container l, the partition 3 being suciently yieldable to take u the shocks and strains resulting from arcing and from unequal expansion. ln addition, the partition 8 serves to separate the container l into separate chambers 4 and 5 in which portions or" a body of mercury 6 are received. When the switch is in one position the portions of the mercury separate at a oint located on the surface of the tube 2 to reak the electrical circuit in which the switch is incorporated, whereas when the switch is in another position the portions of the body of mercury unite in the tube 2 to cause the electrical circuit.

The ends of the outer container or envelope 1 are open and for these ends metallic closures designated generally at 7 and 8 are provided. The closures'may be of any Suitable metal although usually they are constituted of metal substantially unaffected by mercury or at least of metal with acoating having the property of resisting the action of mercury. In addition, the metal of the caps should be non-porous. wWhere a coating is employed it is suliicient to have a non-porous coating. Nickel rolled in vacuum is an example of a non-porous metal that may be used. It is desirable to use a non-porous metal because the switches are usually evacuated to commercial vacuum and then filled with an inert arc suppressing gas. The closures 7 and 8 are of similar construction and take generally the form of a cap which has a plate-like body portion 9 and an annular flange 10. The -iianges 10 of the closures snugly embrace the ends of the container 1 and are fused or welded thereto. This fusing or Welding is accomplished by rotating the container 1 and simultaneously heating the caps and consequently also the end portions of the outer tube. This makes the ends of the outer container suiiciently plastic to enable them to be displaced outwardly by theaction of centrifugal force and thus the plastic end portions of the outer tube are pressed into intimate contact with and are fused and sealed to the heated caps over` a substantial area. The caps or closures may be applied one at a time in accordance with the method disclosed in the copending application of Cliiord Hotchkiss for method of applying closures to glass containers tiled January 7,1928, Serial No. 245,238. Of course, the caps or closures are appliedv before the mercury is placed in the tube. Af

ter the caps have been applied the mercury may be placed in the tube, the air exhausted from the tube and the tube filled with a suitable inert gas through a tubulation 11 provided in the outer container 1 after which the tubulation is sealed.

The closures or caps 7 and 8 are designed to have direct contact with the mercury 6 and consequently to eliminate the necessity ofv using separate electrodes, the closures 7 and 8 serving as electrodes. In many instances, however, it will be desirable to provide extensions 12 and l2 on the closures 7 and 8, the extensions being Welded, soldered, or otherwise suitably iixed to the body portions of the closures, and projecting into the chamber 4 and into the sleeve 2, respectively.

' ner. The shield 13 may be held in position by means of a crimp or corrugation formed in the flange of the cap, (see Figures 1 and 4). The switch construction shown in Figure 2 is identical with thatsfhown in Figure 1 and hereinabove' described except for the omission of the hard glass shield 18 and that one end of the outer container 1 is closed as indicated at 1a and that a ilanged opening 14 is provided on the lower portion of the container '1 adjacent its closed end. This flanged opening 14 is closed by a cap or closure 7 identical in all respects with the closure 7 except that it is smaller and that it does not have an extension 12. The flanged opening 14 provides a trap or well 15 for one portion of the mercury and as such portion of the mercury is always in contact with the cap or closure 7 a it is not necessary to have an ex.

tension of the cap 7 a to insure contact there` with of the mercury.

For the purpose of absorbing or taking up the strains resulting from the expansion of the cap incident to temperature changes brought about by welding, soldering or the like, the body of the cap may be provided with an annular corrugation 2() as shown in Figures 3 and 4. Within the corrugation 20, a bindingpost 21 may be soldered or otherwise suitably fixed to the body of the cap. The corrugation 20 is yieldable or flexible to permit the metal of the cap to expand without breaking down the seal between the cap and the glass container or cracking the glass container when the binding post 1s soldered to the cap or when the temperature of the cap rises for other reasons. The cap of Figures 3 and 4 may be employed in lieu of caps 7 and 8 of the switch shown in Figure 1 or in lieu of caps 7a and 8 of the switch shown in Figure 2.

In Figure 5 another variation of this construction is illustrated and as shown each end of the outer container 1 is ground ofi' to provide a flat end surface against which the periphery of a fiat iron disk D is cemented. A cap C which may be of copper although identical in construction with the caps 7 and 8 (except for the omission of the extensions 12 or 12)-is then fitted over the iron disk and over the end of the tube and is sealed to the tube as before. Each. disk D may have an extension E. In sealing the cap the heating is confined to the ange in a zone slightly Leaders spaced fromthe cement joint between the iron disk and the glass tube. Further, a cement is selected which Will stand up under the heat-1 ing developed therein. This construction has ,5 the advantage of providing tvvo seals for each cap as Well as protecting the copper cap against the action of the arc and against the amalgamating action of the mercury. These advantages will be appreciated when it 4is E@ borne in mind that the cementation of the iron disk on a ground surface provides one seal, the fusion of the copper Bange and glass container another, and that the iron disk entirely isolates all of the surfaces of the copper 3g, cap from the interior of the tube.

While one type of mercury switch is shown, it is to be understood that the invention is capable of embodiment in various diverse types of switches and that the novel con- 20 tainer with its metallic closures :fused and Welded thereto is capable of use in other diverse applications.

With mercury switches embodying the present invention, the closure of the open- 25 ings of the tube is accomplished in a thoroughly satisfactory and yet comparatively inexpensive manner and the character of the closure eliminates the necessity of providing electrodes and lead-in wires sealed throu h 30 ythe glass of the'envelope or container. s the metallic closures are sealed and Welded to the margins of the openings over substantial areas, an extremely durable and reliable con struction is had. .l l

:z5 The invention claimed is:

1. A device of the character described comprising an outer glass container havin an opening and a ground surface surroun ing the same, an iron disk cemented to the ground m surface around the opening ,and a copper cap enclosing'the disk and the end portion of the container and fused and sealed to the container.

2. A device of the character described com- 15 prising an outer container having an opening, an innein closure substantially unaffected by mercury sealed to the container around the opening and an outer .closure fitted over said inner closure and over the adjacent por- 5@ tion of the container and sealed to the container. t

In Witness whereof, I hereto aix my signature. l

PAUL K. CRAMBLET. 

